The present invention generally relates to a bumper for vehicles, especially for passenger cars, and more particularly to a sweep back bumper configured to provide high energy absorption and efficiency in the event of a central collision at the bumper.
A bumper of this type is disclosed by German Published, Unexamined Patent Application No. 3,325,104, wherein, in the event of a central collision, only a small foam volume is subjected to stress because of the sharp backsweep of the bumper. As a result of this configuration, a low energy absorption and poor efficiency is achieved.
To overcome this disadvantage as far as possible, the carrier part of a bumper, according to German Published, Unexamined Patent Application No. 3,325,104, is made highly stable to acquire a load distribution function, thus resulting in greater weight and therefore the need for special supporting measures to prevent the bumper from sagging or drooping over.
An object of the present invention, even on sharply backswept bumpers of less weight having a carrier part which does not perform any pronounced load function, is to support a projecting middle region of the bumper in a controlled manner, in order thereby to make it possible to transmit a high level of force into a skeleton member for supporting the carrier part at a vehicle body even under only slight deformations and, at the same time increasing the efficiency of the bumper.
A regenerable shock absorber arranged, according to advantageous embodiments of the invention, in the middle of the bumper is subjected to stress even in response to only slight deformation of a trim shell of the bumper and therefore has a very high efficiency. Furthermore, by a pushing in of the positive displacement piston of the shock absorber, the sharp backsweep of the bumper is largely cancelled, and the collision energy is transmitted over a wide area into energy absorbing foam of an impact strip and impact damper. The overall system efficiency, in terms of energy reduction, is improved up to 100% in comparison with a pure foam system in backswept bumpers.
Although German Published, Unexamined Patent Application No. 2,243,065 discloses the insertion of a shock absorber, designed as a piston/cylinder unit, between a fixed vehicle part and the middle of a largely non-backswept bumper, nevertheless, in interaction with two further shock absorbers arranged outside the middle of the bumper, these shock absorbers constitute the only energy absorbing elements, and therefore because of the lack of energy absorbing foam as a preeminent energy absorber there is a different initial situation.
Advantageous embodiments of the bumper according to the invention, with expedient developments and forms of construction of the invention, emerge from the further description to follow.
If, according to a preferred exemplary embodiment of the invention, a so-called fender element is interposed between the working cylinder of the shock absorber and the skeleton member, this avoids endangering persons in vehicles which collide sideways with a vehicle equipped with the bumper according to the invention. This safety measure is achieved, since the shock absorber, after retracting, under further increasing stress bends downwards and consequently comes out of the zone putting persons in danger. By a suitable design of the fender element, the latter, by experiencing deformation, can absorb further collision energy.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.